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Scanning spreading resistance microscopy of undoped CdS/ZnSSe multiple quantum well heterostructure
Author(s) -
Sviridov D. E.,
Kozlovsky V. I.,
Sannikov D. A.
Publication year - 2010
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200983252
Subject(s) - heterojunction , optoelectronics , schottky barrier , band gap , materials science , photon energy , schottky diode , quantum well , microscopy , spreading resistance profiling , optics , diode , laser , chemistry , photon , physics , silicon
We carried out scanning spreading resistance microscopy (SSRM) investigation of the undoped CdS/ZnSSe multiple quantum well (MQW) heterostructure under different illumination conditions. To study this effect we illuminated the probe–sample point contact with the radiation of a halogen lamp (HL) ( hν = 1.2–3.1 eV). In spite of the fact that the photon energy of the built‐in atomic force microscope laser (BL) (1.9 eV) is smaller than the band gap energy of the CdS (2.46 eV) and the energy of transitions between ZnSSe valence band and CdS conduction band (2.2 eV) it, nevertheless, influences the visualization, possibly due to Franz–Keldysh effect. It was found that all layers of the structure can be visualized only under negative sample potential, indicating Schottky barrier formation at probe–sample contact. We estimated the carrier concentration in QWs on the basis of simple Schottky diode theory, taking into account spreading resistance R s .